Conventionally, a technique has been known that captures an image of surrounding of an own vehicle by an on-vehicle camera and detects an obstacle based on an edge extracted as a feature point in the captured image, for the purpose of avoiding collision with the obstacle or the like (see, for example, Japanese Laid-open Patent Publication No. 2009-025910)
However, there is a problem in the conventional technique described above in that an edge cannot be extracted for an obstacle with a poor feature point such as a wall with no pattern so that it is difficult to detect the obstacle.